How trees learn

A long line of trees near my home was blown over in last winter’s gales because it had been left vulnerable by foresters who had cut down a pine plantation in order to restore lowland heath.

The silver birch and oak were left at risk because the pines had been sheltering them from the prevailing wind, and they had insufficient time to brace themselves for the onslaught.

Left to their own devices, trees adapt to the prevailing weather, particularly the wind, by thickening their trunks and growing structural roots to hold them in the ground. They also grow spiral grain, which makes them more flexible.

These adaptations are noticeable on the edge of a mature wood where the exposed trees are shorter and have thicker trunks while the sheltered trees in the interior are tall and thin.

Some of these adaptations in windy and exposed areas give single trees or clumps a sculpted appearance as they lean over at seemingly unsustainable angles. This is partly because the prevailing wind damages the growing tips so only the sheltered side grows, and the tree then adapts by bracing its trunk and roots so it does not fall over from its own lopsided weight.

This ability to adapt does raise questions about whether it is sensible to stake newly planted young street trees to protect them against wind damage.

Staking a tree effectively prevents it using natural skills to measure the stresses of the new environment and grow a thicker trunk to cope, leaving it vulnerable to blowing over or snapping at a later date.